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🔥 Nervous system
Key features of the nervous system =
• the nervous system the network of all neurons in the brain and body our primary communication system - it is based on electrical (and
chemical) signals - is made up of sensory, relay and motor neurons
• 2 main functions: 1) to collect, process and respond to information in the environment & 2) to coordinate the working of di erent organs
and cells in the body
• The nervous system is split into 2 parts - CNS & PNS
The structure and function of the central nervous system =
• is made up of the brain and spinal cord
• The brain is the centre of conscious awareness - the outer layer of the brain (cerebral cortex) is highly developed in humans and is what
distinguishes our higher mental functions from those of animals - the brain is divided into 2 hemispheres
• The spinal cord is an extension of the brain and is responsible for re ex actions - it passes messages to and from the brain and connects
nerves to the PNS
• Relay neurons, sensory neurons and motor neurons are present here
The structure and function of the peripheral nervous system =
• sends information to the CNS from the outside world and from the CNS to muscles and glands (ie nervous system that is outside the
CNS)
• Sensory and motor neurons are present here
PNS can be divided into 2 parts:
1) somatic nervous system = transmits info to the CNS and it receives info from the CNS to control voluntary muscle movement - connects
CNS and senses (deals with outside world by communicating with sensory receptors on the skin and muscles to move our limbs - activities in
somatic nervous system are conscious)
2) autonomic nervous system = it transmits info to and from the CNS - it is autonomic because it operates involuntarily (activities in autonomic
nervous system are unconscious) - this can be divided into 2 branches: 1) sympathetic branch = arouses the body (keeps body active and
alert - increasing bodily activities), known as the ght or ight & 2) parasympathetic branch = relaxes the body (keeps body rested and saves
energy - decreasing bodily activities), known as the rest and digest response
• e ects of sympathetic branch on body - increased HR & breathing rate, blood ow diverted from skin to muscles, pupils dilate (allow
more light in to see from far away), saliva production reduced and digestion reduced (as blood ow away from digestive organs),
contracts rectum
• E ects of parasympathetic branch on body - decreased HR and breathing rate, pupils constrict, saliva production increased and
ff fi fl fl fl
🔥 Nervous system
Key features of the nervous system =
• the nervous system the network of all neurons in the brain and body our primary communication system - it is based on electrical (and
chemical) signals - is made up of sensory, relay and motor neurons
• 2 main functions: 1) to collect, process and respond to information in the environment & 2) to coordinate the working of di erent organs
and cells in the body
• The nervous system is split into 2 parts - CNS & PNS
The structure and function of the central nervous system =
• is made up of the brain and spinal cord
• The brain is the centre of conscious awareness - the outer layer of the brain (cerebral cortex) is highly developed in humans and is what
distinguishes our higher mental functions from those of animals - the brain is divided into 2 hemispheres
• The spinal cord is an extension of the brain and is responsible for re ex actions - it passes messages to and from the brain and connects
nerves to the PNS
• Relay neurons, sensory neurons and motor neurons are present here
The structure and function of the peripheral nervous system =
• sends information to the CNS from the outside world and from the CNS to muscles and glands (ie nervous system that is outside the
CNS)
• Sensory and motor neurons are present here
PNS can be divided into 2 parts:
1) somatic nervous system = transmits info to the CNS and it receives info from the CNS to control voluntary muscle movement - connects
CNS and senses (deals with outside world by communicating with sensory receptors on the skin and muscles to move our limbs - activities in
somatic nervous system are conscious)
2) autonomic nervous system = it transmits info to and from the CNS - it is autonomic because it operates involuntarily (activities in autonomic
nervous system are unconscious) - this can be divided into 2 branches: 1) sympathetic branch = arouses the body (keeps body active and
alert - increasing bodily activities), known as the ght or ight & 2) parasympathetic branch = relaxes the body (keeps body rested and saves
energy - decreasing bodily activities), known as the rest and digest response
• e ects of sympathetic branch on body - increased HR & breathing rate, blood ow diverted from skin to muscles, pupils dilate (allow
more light in to see from far away), saliva production reduced and digestion reduced (as blood ow away from digestive organs),
contracts rectum
• E ects of parasympathetic branch on body - decreased HR and breathing rate, pupils constrict, saliva production increased and
ff fi fl fl fl
